Two-cycle internal combustion engine



Sept. 10, 1935.

F. GossLAU TWO-CYCLE INTERNAL GOMBUSTION ENGINE Filed Oct. 2l, 1932 2 'Sheets-,Sheet .l

Sept. 10, 1935. F. GossLAU TWO-CYCLE INTERNAL COM-BUSTION ENGINE Filed OC'E. 21, 1952 2 Sheets-Sheet 2 O I n I f I a f r A ternal combustion Patented Sept. 10, 1935 UNITED STATES 2,013,983 TWO-CY CLE INTERNAL COMBUSTION ENGINE Fritz Gossau, Berlin-charlnfnbrg, asslgnor to Siemens Halske,-

. Germany, Aktiengesellschaft, Siemensstadt, near Berlin, Germany, a

rmany corporation of Ge Application October 21, 1932, Serial No. 638,941 In Germany October 21, 1931 4Claims.

My invention relates to piston cooling of inengines, and more particularly to piston cooling of two-cycle internal combustion engines;

When utilizing the power in internal combustion engines to the greatest possible extent, the piston heads are subjected'to very high temperatures so that a special cooling of the piston parts,

particularly for two-cycle internal combustion engines, becomes imperative. Cooling devices for piston heads have already been proposed. However, these devices have been generally employed in connection with two-cycle carburettor engines with a crank case scavenging pump. Such engines cannot develop a high power, since the operating mixture in this case is utilized as cooling means, and is heated to a considerable extent o n passing over the hot piston head to the detriment of the weight of the cylinder charge.

The passage of the air through the crank case has the further disadvantage that the lubricating oil oxidizes, thus facilitating the formation of slush. This may cause a clogging of the conduits and pumps.

My invention has for its main object to overcome the foregoing drawbacks. To this end, the air supplied by a blower is introduced into the cylinder partly througha hollow space within the piston, closed against the crank case and in part directly into the cylinder.

My invention is illustrated in the accompanying drawings forming part of this specification, like numerals denoting like parts, in which:

Figs. 1 and 2 are longitudinal sectional views of a piston having at the upper part thereof a piston baille,

Figs. 3 and 4 are longitudinal sectional views of 'a piston with a cambered head and,

Figs. 5, 6 and 7 are longitudinal Sectional views showing further modified forms of the piston.

Referring to Fig. l, the cylinder I has an intake 2 for the cooling and scavenging air, an outlet 3 and a flow-over passage 4 opposite to these openings. The piston 5 is provided with a cooling chamber formed by the piston head 9 and a lower transverse wall 8. This chamber separates the piston head from the crank case. The piston is further provided with an inlet port 6 and an outlet port 1 for the cooling air, both terminating in the piston chamber. In the position of piston as disclosed in Fig. 1, the intake opening 2 communicates with the now-over passage I and the interior of the cylinder I through the piston ports I and 1. In this position the air flows through the piston and cylinderto the exhaust opening 3las assist the cooling of the piston head, cooling ribs (Cl. 12S- 65) the lower deadcenter as shown in Fig. 2, the 10 intake 2 is openeddirectly into the cylinder to allow the air to freely pass into the interior of the cylinder. The air then ilows directly over the outer surface of the piston head as indicated by the arrows and forces the residual gas hovering formerly above the piston head, to the upper part of the cylinder and, together with the other residual gases through the exhaust opening 3. In this manner the piston is not only cooled from the inside but also from the outside.

In the embodiment shown in Figs. 3 and 4 the 20 exhaust opening 3 is not arranged at the same side as the intake opening 2 but at an angle 0f 90 to the intake opening 2. The intake 2 is made integral with the cylinder wall and bifurcated so as to form passages I0 and II. In the 25 position of the piston shown in Fig. 3, the cooling air entering at 2 is divided into two currents. The air flowing through the passage I0 directly into the cylinder forces the combustion gases through the exhaust opening 3 with the result 30 that part of that air is also directed over the piston head I2, thus cooling it from above. The other current of air passes through the branch II, the ports 6 and 'l by way of the interior of the piston and cools the head thereof from within.

The air then reaches the interior of the cylinder through the flow-over passage 4, and is also used in this case to expel the combustion gases. To

I3 are arranged on the underside thereof.

In Fig. 4 the piston 5 is shown in its lower dead center. Here the piston is only cooled from the outside, and at the same time the cylinder is charged. Upon the upward movement of the pis- Aton a further current of cooling air passes into the interior of the cylinder.

The arrangement shown in Figs. 5, 6 and 7 differs from that disclosed in Figs. 3 and 4 in that the flow-over passage establishes a communication between the intake 2 and the interior of the cylinder at rst only through the piston chamber by Way of ports 6 and 'l before the scavenging air is able to pass directly into the cylinder. For

this purpose, as shown in Figs. 5 to 7, the branch 55 I0 of intake port 2, (which is called the innerterminal, because it is located nearer the inner part of the cylinder than branch Il, called the outer terminal) is transversely in alinement with the outer terminal of overflow passage 4.

In the position of the piston shown in Fig. 5 the entire cooling air ilows through the intake branch I0 into the interior of the piston and cools the piston head from below. From piston port 1 the air passes through the outer and inner port of the flow-over passage 4 into the cylinder and forces the combustion gases into the exhaust opening 3. In the next lower position of the plston as shown in Fig. 6 part of the cooling air passes directly into the interior ol the cylinder through the intake branch l0, and the other part llows through the intake branch Il into the interior of the piston and through the now-over passage 4 into the cylinder. At that moment both sides of the piston head are cooled simultaneously. When the piston has reached the v lower dead center as shown in Fig. '7, the port 1 is completely closed by the cylinder wall. The cylinder is directly scavenged by the air entering at I0. In the last-described arrangement the ports Gand 1 arranged in the piston 5 and the now-over passage l will again communicate with the interior of the cylinder upon the upward movement of the piston. In this case a part of the charge of the cylinder may flow again through the interior of the piston which in the meantime has been sufllciently cooled down.

The particular advantage of the invention lies in the fact4 that the cooling air-owing through the piston and being thereby intensely heated up, since it comes into contact with the piston when the latter attains the highest possible temperature-substantially serves to expel the combustion gases. In this case the volumeV of air which is employed to expel the combustion gases may, consequently, be utilized for the cooling of the piston. That this volume of air is thereby intensely heated and expands is not of any importance with respect to the useful charge in the cylinder or to the power of the motor, since most of this air leaves the cylinder again 'together with the combustion gases. The expansion of the scavenging air by the heat radiating from the piston rather supports the scavenging of the cylinder. On the other hand, the air which is introduced into the cylinder at the lower dead center position of the piston is far less hot. It also expands to a lesser degree, and serves substantially to charge the cylinder, after the hottest portion of this air has also passed into the atmosphere through the exhaust opening 3. The charge of the cylinder is, therefore, effected with colder and consequently denser air, whereas the expulsion of the combustion gases is carried out by means of a smaller weight of scavenging air whose volume has increased owing to the heat taken up. In this case a portion of the powerrequired for scavenging the cylinder which has hitherto been performed by the blower is consequently accomplished by the heat radiating from the piston. The cooling air for the piston which has heretofore been in most cases sent out into the atmosphere is utilized here for scavenging the cylinder, thus effecting a saving in power, which was heretofore required for the blower.

The invention is especially applicable to highspeed engines, particularly to aeroengines where the highest possible efllciency is required and where now/the power or the blower which was heretofore necessary for the piston cooling can be reduced to a minimum.

I claim 'as my invention:-

1. In an internal combustion engine the combination with a crank case and a working cyl- 5 inder having intake and exhaust ports in its wall and a now-over passage in the 4cylinder wall located opposite to said intake port, of a working piston in said cylinder having a cooling chamber adiacent to its head closed toward the crank case, 10 said chamber having inlet and outlet ports at diametrlcally opposite piston sides and adapted to register respectively with said intake and said flow-over passage during the piston movement to permit scavenging air supplied to said intake to 15 reach the cylinder indirectly by way of said chamber during the outward stroke of said piston, said int e port being arranged in a position with respellI to the piston path which permits scavenging air supplied to said port to enter the cylinder vdirectly when the piston is located about its outer dead center position.

2. In an internal combustion engine in combination a crank case, a working cylinder and a working piston in said cylinder, said cylinder having an exhaust and an intake port in its wall disposed side by side in the direction of the cylinder axis, and a flow-over passage arranged in the cylinder wall diametrically opposite said intake port, said piston having a cooling chamber 30 below its head, closed against the crank case, and having an inlet and an outlet port arranged to register respectively with said intake port and said flow-over passage, during the piston movement to permit scavenging air supplied to said 35 intake to reach the cylinder ilrst indirectly by way of said chamber during the outward stroke of said piston, said intake port being arranged in a position with respect to the piston path which permits scavenging air supplied to said port to 40 enter the cylinder directly when the piston is located about its outer dead center position.

3. In an internal combustion engine in combination with a crank case and a working cylinder having in its wall an intake port and an ex- 45 haust port disposed circumferentially at right angles to the intake port and a Ilow-over passage disposed diametrically opposite said intake port, of a working piston in said cylinder, having a cooling chamber below its head, closed toward 50 the crank case, said chamber having inlet and outlet ports at diametrically opposite piston sides, and adapted to register respectively with said intake port and said ilow-over passage during the piston movement, said cylinder intake port be- 5 5 ing divided in the direction of the cylinder axis into two separate branch ports to permit scavenging air supplied to said intake port to flow during the outward piston stroke into said cylinder partly directly by way of one of said branch 60 ports and partly indirectly through said chamber by way of the other branch port and said flowover passage, for cooling both sides of the piston head, and to permit only direct ilow of scavenging air into the cylinder by way of both branch 65 ports when the piston is located about its outer dead center position.

4. In an internal combustion engine in combination with a crank case, a working cylinder having in its wall an intake port and an exhaust port 70 disposed clrcumterentially at right angles to the intake port and a flow-over passage disposed dlametrically opposite said intake port, said intake port and said passage each having an inner and an outer port terminal located side by side in 75 v 2,013,983 the direction of the cylinder axis, the outer owover terminal passage being located on the same transverse cylinder level as the inner intake port terminal, a working piston in said cylinder having a cooling chamber below its head, closed toward said crank case, said chamber having an inlet and an outlet port at diametrically opposite piston sides adapted to register respectively with said intake port and said ow-over port 10 terminals during the piston movement, whereby during the outward piston stroke scavening air, supplied to said intake port terminals, flows into said cylinder yrst only indirectly'by Way of said cooling chamber, then partly indirectly by way of said chamber and partly directly by way of the inner intake terminal, and whereby the scavengng air flows into the cylinder only directly by way of the inner intake terminal when the piston is located about its dead center position.'

- FRITZ GOSSLAU. 

